Some guidelines recommend that men with rapidly rising prostate-specific antigen (PSA) undergo prostate biopsy even if their PSA remains in the “normal” range and they have no other signs of prostate cancer. A recent study, however, suggests that PSA velocity is a poor predictor of prostate cancer, and may lead to many unnecessary biopsies. These results were published in the Journal of the National Cancer Institute.
Men 50 years of age or older in the United States are often offered PSA testing for the early detection of prostate cancer. The test may be offered at a younger age to men at high risk of prostate cancer. The PSA test measures proteins that are produced and shed by the prostate. PSA levels tend to be elevated when prostate cancer is present, but levels can also be elevated in benign (non-cancerous) conditions affecting the prostate. Men with a high PSA level may undergo a prostate biopsy in order to determine whether prostate cancer is present.
Because PSA level is not a perfect predictor of prostate cancer, researchers have continued to search for ways to improve prostate cancer screening. The addition of information about PSA velocity (the rate at which PSA is rising) is sometimes considered in addition to PSA level. It’s been uncertain, however, whether PSA velocity adds important information above and beyond what’s provided by other measures of risk, and whether it’s useful in guiding decisions about prostate biopsy.
To assess the information provided by PSA velocity, researchers evaluated information about more than 5500 participants in the Prostate Cancer Prevention Trial. All of the men underwent had a prostate biopsy at the end of the study regardless of their PSA level or PSA velocity.
- PSA velocity was correlated with the likelihood of cancer. After the researchers accounted for several other indicators of risk, however, such as age, race, PSA levels, and result of digital rectal exam, PSA velocity was no longer an important predictor of risk.
- The researchers also considered the question of whether men with rapidly rising PSA would benefit from a prostate biopsy even if their PSA remained in the normal range and the digital rectal exam was normal. They found that a large majority of men in this category (roughly 80%) did not have cancer. This suggests that using PSA velocity to guide biopsy decisions would result in many unnecessary biopsies.
The researchers write “There was little evidence that PSA velocity adds an important level of predictive accuracy to either standard predictors or PSA alone.” They also conclude that PSA velocity should not be included in prostate cancer screening guidelines.
Reference: Vickers AJ, Till C Tangen CM, Thompson IM. An empirical evaluation of guidelines on prostate-specific antigen velocity in prostate cancer detection. JNCI. 2011; 103 (6): 462-469.